Producing specific magnetic information on a medium such as paper money, a note and a negotiable security is one of important means of a modern anti-counterfeiting technology. Along with development of a production technology, application of a magnetic information anti-counterfeiting technology is continuously enhanced. For example, banknotes of many countries (such as Renminbi, U.S. dollars, Euros, so on) internally include magnetic information with rich content. Recognition over the specific magnetic information on the medium such as the paper money, the note and the negotiable security is also necessary anti-counterfeiting detection means.
In order to implement detection, a magnetic image sensor is provided in a related technology. In the magnetic image sensor, miniature magnetic heads are continuously arranged in the whole reading and recognition range to form a linear array of the miniature magnetic heads, thereby implementing reading and recognition on magnetic information in the whole reading range. However, each single magnetic head is relatively larger in size, and a reading and recognition range on each magnetic head occupies a small part of a range of the magnetic head, so that a large range between the magnetic heads are outside a effective reading range of the magnetic heads, that is, it is impossible to read the region between the magnetic heads. When such a magnetic image sensor is used, the magnetic information at a gap between the magnetic heads may get lost.
A magnetic sensing device is further provided in the related technology. Multiple recesses linearly formed along a side length direction of an internal bracket are formed in an upper surface of the internal bracket of the magnetic sensing device. A magneto-resistive element is accommodated in each recess, and the magneto-resistive elements are arranged into a linear array within a reading and recognition range to read and recognize magnetic information in the reading range. In this technology, the magnetic head is replaced with the magneto-resistive element, and the gap between the magneto-resistive elements is greatly reduced, so that the whole magnetic sensing device is miniaturized. However, the magneto-resistive element has an excessively large linear dimension, the magnetic information in the range of the dimension is not able to be distinguished in detail, the read magnetic information on a medium is very blurred, and details of the magnetic information is not able to be distinguished. Therefore, when finer characteristics of magnetic information regions are required to be judged, this magnetic sensing device is incapable.
A magnetic sensor device is further provided in the related technology. Magnetic sensing elements are array magnetic sensing elements which used for reading magnetic characteristics of a medium. Magnetic sensing elements are configured at an end part of a plane sidewall of one side of a frame along a direction of a reading range, and the magnetic sensing element is point-like or strip-type. In this technology, a resolution of the magnetic sensing elements manufactured by a printing sintering process is able to reach more than 50 DPI, so that a problem about a magnetic information resolution capability is solved. However, a deviation of the magnetic sensing elements obtained by the printing sintering process is very great, usually about 20%, and even though the magnetic resistance deviation is reduced by a method for changing a resistance, the deviation may also be about 3%-5%. For a 5V common electrode voltage, a voltage deviation of an order of magnitude of at least 150 mV is produced. A magnetic Signal voltage which is able to be detected practically is usually with an order of magnitude of 10 mV, that is, a signal difference (noise signal) caused by a practical magnetic resistance deviation is far greater than an effective signal, so that a great difficulty is brought to signal processing, and it is very difficult to accurately separate the effective signal from the noise signal under a normal condition.
For the problem of relatively stronger noise signal caused by a magnetic resistance deviation of a magnetic image sensor in the related technology, No effective solution has been proposed yet.